See How I Used Soda Crystals to Remove Moss and Algae on My Patio

published Jun 17, 2023
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I recently moved to a home with a garden for the first time, which means that I’ve got a little patch of patio in the back. I’m looking forward to getting the patio furniture out and enjoying al fresco dining this summer — but my new patio needed a bit of work before it was ready for hosting.

As we moved in, my father-in-law kindly cleared all the weeds for us, but the actual patio paving stones were still coated in moss and algae. After a little internet research, I discovered that you can use soda crystals to clean up a patio, which I already had in my pantry and are a lot cheaper than patio cleaning fluid.

Soda crystals are also more environmentally friendly than harsh cleaning chemicals and are non-toxic to people, which is very important for someone like me, with a baby who is just learning to crawl. If you have pets, though, you may want to keep them indoors while using soda crystals to clean your patio, as they can be toxic to animals.

Soda crystals (also known as washing soda, sodium carbonate, or soda ash) are similar to baking soda, but with a higher pH. If you don’t already have some at home, you should! They’re cheap and versatile. 

Credit: Zoe Pickburn

As well as cleaning your patio, soda crystals can be used to strip laundry and towels, unclog drains, and make an all-purpose spray. The other benefit to using soda crystals to clean the patio is that it can kill any weeds that are growing between paving stones, too.

So I decided to give cleaning my patio with soda crystals a go — and it actually worked surprisingly well. I tested the method out on one stone slab first, and now that I can see how well it worked, I’m going to clean up the whole patio using soda crystals.

Credit: Zoe Pickburn

How to Clean Your Patio with Soda Crystals 

Here’s how you can clean your patio with soda crystals, step by step, so it’ll be clean this summer.

  • Step 1: Clear debris. First of all, clear any obvious debris off your patio, then get the stones wet, either with a hose or a watering can. You want them to be damp, not soaked.
  • Step 2: Remove lumps in the package. Make sure that you’ve shaken your pack of soda crystals to separate any lumps. I missed this step and made the mistake of getting a big lump on the patio, which I then had to break up and spread across the stone with my hands. 
  • Step 3: Spread soda crystals out. Spread the soda crystals over the patio in a thin, even layer. I did this with dry soda crystals to test on one corner, but to clean a larger area you can mix half a cup of soda crystals with a liter of hot water and pour that over the area.
  • Step 4: Let it sit. Then, leave the crystals to do their magic for 24 to 48 hours. 
  • Step 5: Scrub it. Finally, you need to give your patio stones a really good scrub with a hard bristle brush. This part does take a bit of elbow grease and it is so satisfying to see the clean paving emerge as you scrub. You can add a bit more water at this stage to scrub away the white powdery crystals.
  • Step 6: Rinse it off. Then just use a hose or watering can to rinse the rest of the powder away.